Development of Models for Prediction of Short-Term Fate of Dredged Material Discharged in the Estuarine Environment.

Abstract

The Dredged Material Research Project (DMRP) has as one of its objectives to provide more definitive information on the environmental aspects of dredging and dredged material disposal operations. This study was conducted to fill the need of that program for the capability of predicting the short-term fate of dredged material discharged in the estuarine environment. Two numerical models were developed: one for the instantaneous dumped discharge and one for fixed or moving jet discharge. The models account for land boundaries, depth variations in the estuary, ambient current variations in three dimensions and in time, and variations of ambient density profiles in time. The models are capable of tracking up to twelve classes of solid particles plus the fluid fraction of a discharge through convective descent, dynamic collapse, and passive diffusion phases. The models were developed by coupling the appropriate short-term dynamic portions of the Koh-Chang oceanic disposal model with an extensive modification of a model, originally developed by Fischer, for predicting the fate of chemical wastes in an estuary. Although the models themselves are extremely complex, the input data requirements for most cases are quite simple and should allow the first-time user to run a simple case in a few hours. The models have undergone limited testing and the results produced are physically reasonable. A program of model exercise and testing is strongly recommended, however. When the models are used in cases involving complex ambient velocities, the models will be extremely dependent on good-quality velocity data. (Author)